Electrically heated tile



Sept. 19, 1950 w. H. Ross ELECTRICALLY HEATED TILE Filed April 29, 1948 INVENTO/l Wall'er H Ross.

ATTORN Y Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE ELECTRICALLY HEATED TILE Walter H. Ross, Westfield, N. J.

Application April 29, 1948, Serial No. 23.930

3 Claims. 1

This invention relates to platforms, including steps, stairs, gangways, treadles and the floors of vestibules, and particularly to the heating of the surfaces of such platforms, for the prevention of icing conditions, as well as the acceleration of the process of moisture evaporation from such surfaces, and the maintenance of a surface temperature that provides a satisfactory measure of comfort to operators, attendants, or other persons having occasion to stand on or traverse such surfaces.

On surfaces of the character indicated, the formation of ice creates a serious hazard, and this hazard is greatly aggravated by the poor visibility that frequently prevails at the point where the icing condition is most dangerous; the poor visibility being due to the lack of adequate illumination upon the iced surface, or to the obstruction of vision by the presence of other persons at the point of entrance or exit, adjacent the iced surface, or to a combination of these factors.

The surfaces of steps, treadles, and vestibule floors are frequently corrugated,serrated,knurled, or otherwise relieved, in an effort to reduce the slipperiness thereof; but even with such treatment the danger of slipping is not greatly lessened, particularly during freezing weather, for when freezing occurs the irregularities of the surface are soon obliterated, and in their places there is formed a smooth coating of ice constituting the greatest possible hazard. The stairways, gangways, turret platforms, and exposed decks of marine vessels, in addition to other surfaces mentioned above, are peculiarly susceptible to such icing and over-wetting tendencies.

An object of the present invention is to provide a surface covering which is inherently ice-proof and which, because ice can not form thereon, will provide a sure footing under all weather conditions.

Another object of the invention is to provide a tile-like material having high wear resistance as well as good heat conducting qualities, and also having an electrically conductive element of high heat capacity and resistivity to corrosion permanently integrated therein.

A further object of the invention is to provide a platform, floor segment, or step pad of thermosetting plastic composition, into which composition there is inserted, a network of current conducting members through which heating current may flow when an external current source is connected to the exposed terminals of said network; the fusion point of the selected plastic material being substantially higher than the max- 2 imum temperature likely to be developed in sai heating network by reason of current flow therethrough, thus precluding any possibility of deterioration by combustion or carbonization.

While floor segments and step pads of the character herein disclosed are particularly desirable for use on the steps and other passage-ways of buses, trolleys, and other conveyances, including marine vessels, the invention is not limited to this particular application. It may be applied to the construction of any flooring materials intended for use as surface covering in locations exposed to moisture and freezing temperatures.

In the accompanying drawing, illustrating one embodiment of the invention, Fig. 1 is a plan view of the lower section of a mold in which a floor segment or step pad is to be molded, and into which mold there has been inserted a grid assembly; and Fig. 2 is a perspective view of the finished pad, or tile, as it appears after removal from the molding machine.

Referring to said Figs. 1 and 2, the lower mold section 3 is shown as of rectangular shape, although of course the shape and dimensions may vary to suit the requirements of the particular use to which the tiles or pads are to be applied. The mold section 3 will have a depth approximately equal to one-half the thickness of the tile to be molded therein, and the upper mold section (not shown) will be of corresponding dimensions. Preparatory to the molding operation the constituent ingredients of the product are thoroughly mixed, permitting an even distribution of the component parts. By any suitable mechanical means this dry mass is introduced into the mold cavity. During this process the grid assembly 4 will be placed centrally within the mass, being supported by an under-portion of the compound consisting, to a large extent, of fibrous structure, the grid being then covered by a facing layer having a predominance of abrasive grain or grit. The grid 4 will be of high resistance material, such as nickel chromium alloy wire or ribbon, and will have its terminal portions 5, 6 so placed as to be available for reception of plug-in prongs of an external supply circuit, after the completed tile has been installed at its place of use.

Following the introduction of the mass, including the grid element, into the production mold, the two complementary halves of the mold are brought together, after which the mold is placed Within a steam-heated hydraulically operated press. An adequate pressure is imposed upon the mold and constant temperature is maintained 3 for a pre-determined period. Thus there is produced a compact structure, the component parts of which are strongly bonded through the medium of a thermo-setting resin.

To provide the maximum capacity for withstanding abrasive wearing forces, and also high dielectric strength and heat resistivity, I prefer to employ, as the composition to be introduced into the mold as a covering for the grid assembly 4, a mixture of abrasive grain or grit, to which are added the desired amounts of inert fibrous and other fillers, color pigments (to obtain the desired coloring, which of course may vary to suit different situations) and heat-resisting thermosetting resin to plasticize and bond the entire mass into a compact, homogeneous, hard-wearing product having the desired degree of toughness and malleability to insure greatest durability. I do not claim novelty for such a composition, per se, as it is now obtainable on the open market; what I do claim is the combination with such a composition of the novel electrical heating means whereby the finished product can be regulated and maintained at temperatures sufliciently elevated to prevent ice formation thereon, and at the same time to provide a suitable degree of comfort to all persons having occasion to stand on, or traverse, the surface of the product so constructed.

The resins employed should be such as to produce a thermo-setting action at approximately 350 degrees Fahrenheit; and as an adequate heating of the surface, even during severe freezing weather, can be assured with the use of power connections of ordinary voltage and wattage, the internal temperatures will not exceed 150 degrees Fahrenheit at any time. Hence there is no likelihood of injurious over-heating of the product.

A pad inch in thickness, constructed in accordance with this disclosure, has been found to be capable of resisting break-down at voltages up to 29,000 even when wet, and up to 30,000 when dry. This is evidence of its high dielectric strength. Moreover, because of its toughness there is very little possibility of wear to such a point as to cause exposure of the heating grid.

If it is desired to have automatic regulation of the current supply to the grid assembly, thermostats or other controls may of course be incorporated.

The life expectancy of an electrical element depends upon the temperature range at which it operates, provided there is no corrosion factor present. In my invention the normal voltage will at all times be low and there is little if any opportunity for corrosion, as the grid 4 is hermetically sealed Within the finished unit.

The word grid as used in the appended claims is to be understood as embracing any suitable arrangement of wires, strips, or coils, or even a single conductor having component sections distributed about the full area of the tile, as indicated in Fig. 1.

What I claim is:

1. A readily portable grid-bearing tile having a maximum surface area of 900 sq. inches, and having an upper layer containing wear-resistant abrasive, a current-conducting grid of a high resistance material beneath said upper layer, a lower layer supporting said grid, a pair of exposed terminals connecting with said grid and adapted to receive circuit-completing elements for the supply of electrical energy thereto, and a thermo-setting bonding agent for permanently uniting said upper and lower layers to said grid, and to each other, upon application of heat and relatively high compacting pressure thereto.

2. A grid-bearing tile as defined in claim 1, wherein the compacting pressure serves to compress the two layers into an integral pad of a thickness on the order of of an inch.

3. A grid-bearing tile as defined in claim 1, including a surface area comparable to that of conventional floor tiles, and a thickness on the order of of an inch.

WALTER H. ROSS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,062,199 Stephenson May 20, 1913 2,138,217 Sutter Nov. 29, 1938 FOREIGN PATENTS Number Country Date 113,192 Australia June 12, 1941 225,627 Great Britain Dec. 8, 1924 

